'Fire' in the Bible

(The Shulammite Bride)“Under the apple tree I awakened you [to my love];There your mother was in labor with you,There she was in labor and gave you birth.“Put me like a seal on your heart,Like a seal on your arm;For love is as strong as death,Jealousy is as severe and cruel as Sheol (the place of the dead).Its flashes are flashes of fire,[A most vehement flame] the very flame of the Lord!